Electronic forms often access data from data sources through data connections. These data sources persist data, such as a text file with a list of names, a production database storing numbers, and the like. Electronic forms may communicate with these data sources through data connections to make editing the electronic form more scalable, maintainable, easy to use, or full-featured.
For example, data connections generally permit an electronic form to provide information to a user to aid the user in editing the form. In some cases data connections are enabled through connection to a data source over a communications network, such as the Internet. Assume, for instance, that a user is attempting to register for college classes using an electronic form. It may be easier for a user to complete the form if the form is able to respond to queries initiated by the user with data retrieved from a data source. The form may have, for example, a field for entry of a department at the college. The user might know and be able to enter the name of the desired department. But if the user does not know it or does not want to have to type it in, the user may find it easier to select a department from a provided list of departments. The user may initiate a query for this list, such as by clicking on a dropdown list or a button on the form. In response, the form may connect to a data source having this list, like a registration department's computer at the college, and provide this list to the user.
In some situations, however, an electronic form may not have access to—or a user may not want the form to communicate with—a data source. For example, the user's computer may not have access to a communication network (e.g., the Internet) or the data source may be inaccessible because of a failure of the user's computer or a network's server. In either case, when an electronic form does not connect to a data source, the electronic form's performance may degrade. The form may fail to open without access to a data source. Or, if the form opens it may give an error message if the user initiates a query that the form cannot answer without connecting to the data source.